Generally, when an anomaly is detected on an equipment item, the procedure to be followed comprises two main steps:                access to information concerning what the equipment item affected by the anomaly “saw” at the moment when the anomaly was declared;        application of a program of tests in order to understand the causes of the anomaly observed.        
The known means for trying to successfully conduct these investigation steps lack flexibility; furthermore, they are difficult to implement and costly. Moreover, they generally entail dismantling assembled equipment items or introducing devices into the overall system including the equipment item affected by the anomaly. Such interventions, often time-consuming, also require consents, which can potentially take a long time to obtain, allowing the intervention.
In practice, these days, when investigations are carried out, on a satellite that is at least partially assembled, in order to determine the causes of an anomaly occurring on an equipment item, it is necessary to communicate with the equipment item or items concerned, inside the satellite, from “ground” communication means, via:                electrical interfaces of the equipment item or items concerned, in nominal mode, called driven mode;        means for radiofrequency communication, by uplinks and downlinks, generally in the S band or in the Ku band, in nominal mode, called RF (radiofrequency) mode;        appliances, or “exploded boxes”, that make it possible to sample and analyze an analog signal at any point of the equipment item, in anomaly mode.        
Moreover, digital signals can, subject to certain conditions, be sampled and analyzed using sensors based on the principle of a Hertzien loop.
The complexity, lack of flexibility, the lead times required for a complete investigation, and the costs of these known means used to search for the causes of an anomaly detected on an equipment item are incompatible with the “real time” nature and the objectives of simplicity, robustness and discretion desired for such applications: they therefore constitute as many defects as the present invention seeks to resolve.